I tried to find out, how many countries use a 12h clock instead of a 24h clock, but the best I could come up with is Wikipedia:

"The 24-hour clock enjoys broad everyday usage in most non-English speaking countries, at least when time is written or displayed. In some regions, for example where German, French and Romanian are spoken, the 24-hour clock is used today even when speaking casually, while in other countries the 12-hour clock is used more often in spoken form."

and this link: https://travel.stackexchange.com/questions/34950/which-large...